Relationships between management, soil health indicators, routine soil tests, and corn yield in organic grain systems

Abstract Biological indicators, including particulate organic matter C (POMC) and N (POMN), potentially mineralizable N (PMN), fluorescein diacetate (FDA) hydrolysis, and permanganate oxidizable C (POXC), may prove useful soil health indicators if they can link management to soil productivity. We evaluated relationships between indicators of soil health and routine soil tests, with management practices, and corn ( Zea mays L.) yield in organic grain systems in the US Midwest. For this, we used site‐specific covariates and management typologies that describe N fertility, cropping intensity, and crop diversity. Soil samples were collected from 43 fields within 2 weeks of corn planting. Fields amended with animal manure had significantly higher POMC, POMN, PMN, and inorganic N concentrations than those relying only on green manure. Both POMC and potassium concentrations increased with cropping system diversity. Crop diversity was also positively related to POXC, FDA, and calcium when perennials were used in the rotation. Regression models relating soil health indicators to crop yield performed best for POM attributes and ranked POMN > POMC > POM C:N. The best model fit for POMN and crop yield included soil organic carbon, texture, and seasonal temperature as covariates. Results reveal shortcomings in management typologies applied to complex farming systems and demonstrate how regionalized on‐farm studies can account for site‐specific factors influencing the effects of management on soil health. Results suggest POM has promise as a soil health indicator, and future work should quantify its contributions to soil N supply, soil physical condition, and crop yield.